Such a band cylinder is known from DE-AS 1 293 037, in which the sealing elements are cylindrical bars of elastic material and arranged in pairs on both sides of the band and the band guide comprises a plate, which is provided with a slot for the band to pass through and which is held detachably at the cylinder cover by means of a cover piece. The cover piece includes an expansion of the receiving chamber, which is filled with felt abutting the band. When the band is moved, the cylindrical bars and the felt generate a relatively large degree of friction, thus impairing the function of the working cylinder. In addition, the differing mounting supports of the cylindrical bars, band guide and felt can cause a center offset of these parts, thus causing a further reduction in the function.
The band of such working cylinders is usually designed as a flat steel or plastic band.
From Austrian patent 364 621 it is known to arrange a lubricant pad for the band in front of a seal designed like a conical plug; when the band is moved, the lubricated band is supposed to force the seal through friction into a housing cone and thereby to cause a sealing contact pressure against the band. Despite the lubrication, here, too there is noticeable friction; in addition, no band guide is provided.
German published patent application 24 04 244 discloses a band cylinder which differs from the afore-mentioned features and which, to seal the band, comprises a bar-like lip seal supported by a pressure medium and having one lip which abuts the wide side of the band and a second lip which abuts the wall of a receiving chamber for the lip seal.